Numerical Computations of Unsteady Aerodynamics of Maneuvering Projectiles

This paper describes a multidisciplinary computational study undertaken to model the flight trajectories and the free-flight aerodynamics of finned projectiles both with and without control maneuvers. Advanced computational capabilities in computational fluid dynamics (CFD), rigid body dynamics (RBD) and flight control system (FCS) have been successfully fully coupled on high performance computing (HPC) platforms for physics-based “Virtual Fly-Outs” of munitions. Time-accurate Navier-Stokes computations have been performed with the commercial CFD++ software to compute the unsteady aerodynamics associated with the free flight of finned projectiles using an advanced scalable unstructured flow solver on a highly parallel Linux Cluster. Progress made in the exploration of new techniques to efficiently generate a complete aerodynamic description consisting of both static and dynamic aerodynamic coefficients for projectile flight dynamic modeling is described. A new procedure that uses time-accurate sweeps allows rapid generation of static aerodynamic coefficients. Another method uses an unsteady, time accurate CFD simulation that is tightly coupled to a RBD projectile flight dynamic simulation and can generate both static and dynamic coefficients. A set of short time snippets of simulated projectile motion at different Mach numbers is computed using the integrated CFD/RBD/FCS software and employed as baseline data. The technique is being exercised on a finned and a canard-controlled projectile. The effect of canard angle deflection on the aerodynamics of the canard controlled projectile is currently being computed using the virtual fly out method and the CFD/RBD/FCS software.